The games help support wounded veterans, and the stars, along with others, recite the poem Invictus, by William Ernest Henley, as well as deliver a message, in the video.

"Our Armed Forces community have made huge sacrifices in recent years," says Craig, who urges people to "give something back to those who give so much."

Will.i.am, who ends the video with the line "I am Invictus," adds in a statement: "This is all about using the power of sport to inspire recovery and support rehabilitation. I want to wish all the competitors the very best of luck for this inspiring event."

More than 400 wounded, injured and sick servicemen and women from around the world are set to compete in the Invictus Games in venues around London, with the event culminating in a concert at the former Olympic park.

"Ultimately," Prince Harry says in a statement, "this is about the men and women who have given so much and deserve our support, in their recovery, rehabilitation and on leaving the armed forces. I know people will want to join me in cheering them on from the sidelines."